Lets look at whats happened in Home Theater in the last 2 years,technology is moving at a lightning pace,features are being added allmost on a weekly basis,prices are dropping like fly's,following this pattern your allmost assured that what ever you buy will be obsolete or hold little value within the next 2 years.
My point is this,you want/need to work on your HT room,why not put upgrading electronics on the back burner & finish your room,after your room is done then & only then start thinking about upgrading electronics,ive found out after many years in this hobby that in most cases there is no such thing as an upgrade,only lateral moves that require spending large amounts of cash.
Buying used tv's is probabally not a good move but used speakers & electronics is a very safe bet,you can keep costs down & quality levels extremely high from buying gear from somebody else who has upgrade fever,let somebody else loose 60% just so they can have a new feature.
Here are a few examples of what buying from people with upgrade fever can get you & you wont touch this kinda quality of receiver for $400 new at any store.
http://cls.audiogon.com/cgi-bin/cls.pl?miscrcvr&1198459516
http://cls.audiogon.com/cgi-bin/cls.pl?miscrcvr&1198149172